If 9999=4
8888=8
1818=4
1212=0
then 1919=?

???????????? 9999=4=1818 ??????????????
by
1919 = 2
by
8888+1818-9999+1212=1919, so 8+4-4+0=8... Therefore answer is 8..
by
by
by

It is number of circles in the number

8 has 2 circles, 9 has 1
by
answer is 2. number of circles in each digit.. 1919 has 02 circles in 9
by
1919=2, Just count the circles in the number.

8888 has 8 circles, whereas 9999 has 4 circles.
by
by

How?
If you observe carefully, right side number is equal to total number of circles in the left side numbers. thus the answer to 1919 should be 2.

by
count the circle in  9999 has 4 and 8888 has 8 so on.
by
The reasoning is as follows:
For 9999, there are 4 closed regions (consider the top part of the digit 9) and no other digits, so 9999=4
For 8888, there are 8 closed regions (consider the top part and the bottom part of the digit 8) and no other digits, so 8888=8
For 1816, there are 3 closed regions (2 of the digit 8 and 1 of the digit 6) and 2 other digits, so 1816=3*2=6
For 1212, there are 0 closed regions (digits 1 and 2 do not have closed regions) and 4 other digits, so 1212=0*4=0

Use same calculation for 1919, there are 2 closed regions (digit 9) and 2 other digits, so 1919=2*2=4

Given a number N, f(N) is defined as follows:
Count the number of closed regions for each digit of N, and get total T.
If every digit has closed regions, then f(N)=T
Else if R digits do not have closed regions, then f(N)=T*R
So f(9999)=4 and f(8888)=8 and f(1816)=6 and f(1212)=0 and f(1919)=4.
by
2 is the answer.its equal to the number or circles in d left side.
by
If 9999=4 8888=8 1818=4 1212=0 then 1919=? ans .2
by
2 circules
by
2 The number of o's 9 upper cross-section is an o 8 if cross sectioned we have two o's
by
9999=4    9=1  >> 1+1+1+1=4

8888=8   8=2  >> 2+2+2+2=8

1818=4   1=0  >> 0+2+0+2=4

1212=0   2=0  >> 0+0+0+0=0

then 1919= >>0+1+0+1=2
by